Vehicles, such as light-duty cars and trucks and heavy-duty tractor/trailers, can include “telematics” systems that monitor information describing the vehicle's location and diagnostic conditions. Such telematics systems typically include a conventional global positioning system (“GPS”) that receives signals from orbiting satellites and a processor that analyzes these signals to calculate a GPS “fix”. The fix, which features data such as the vehicle's latitude, longitude, altitude, heading, and velocity, typically describes the vehicle's location with an accuracy of about 10 meters or better.
Telematics systems can include circuitry that monitors the host vehicle's diagnostic system. As an example of a diagnostic system, light-duty automobiles and trucks beginning with model year 1996 include an on-board diagnostic (OBD-II) system as mandated by the Environmental Protection Agency (EPA). OBD-II systems typically operate under one of the following communication protocols: J1850 VPW (Ford); J1850 VPWM (General Motors); ISO 9141-2 (most Japanese and European vehicles); Keyword 2000 (some Mercedes and Hyundai vehicles); and CAN (a newer protocol used by many vehicles manufactured after 2004). OBD-II systems monitor the vehicle's electrical, mechanical, and emissions systems and generate data that are processed by a vehicle's engine control unit (ECU) to detect malfunctions or deterioration in performance. The data typically include parameters such as vehicle speed (VSS), engine speed (RPM), engine load (LOAD), and mass air flow (MAF). The ECU can also generate diagnostic trouble codes (DTCs), which are 5-digit codes (e.g., “P0001”) indicating electrical or mechanical problems with the vehicle. Most vehicles manufactured after 1996 include a standardized, serial 16-cavity connector (sometimes referred to herein as an “OBD-II connector”) that makes these data available. The OBD-II connector serially communicates with the vehicle's ECU and typically lies underneath the vehicle's dashboard.
Heavy-duty trucks typically include a diagnostic system, referred to herein as a “truck diagnostic system”, which is analogous to the OBD-II systems present in light-duty vehicles. Truck diagnostic systems typically operate a communication protocol called J1708/J1587 or J1939 that collects diagnostic information from sensors distributed in the truck, processes this information, and then makes it available through a 6 or 9-pin connector, referred to herein as a “truck diagnostic connector”, which is usually located in the truck's interior.